The structure of the mature equine sperm chromosome and its mechanism of release during fertilization will be investigted by physical, chemical, enzymological, and microscopic techniques. Specifically, the structure and organization of the DNA componenet of the sperm chromosomal fibers will be studied using x-ray diffraction, circular dichroism spectroscopy, birefringence microscopy and transmission electron microscopy. The major protein componenet of these chromosomal fibers will be characterized as to amino acid content and linear sequence and its binding to DNA studied. The mechanisms for the reductive breakdown of the disulfide crosslinkers within the packaged chromatin fibers of equine sperm head pieces during fertilization will be studied. These enzymological studies will focus on the search for a disulfide reductase activity in equine gametes, also, observations of the events in natural and artificial fertilization surrounding sperm chromatin release will be undertaken.